<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <link rel="stylesheet" href="./css/index.css" />
    <title>记事本</title>
</head>

<body>

    <!-- 主体区域 -->
    <section id="app">
        <!-- 输入框 -->
        <header class="header">
            <h1>小黑记事本</h1>
            <input placeholder="请输入任务" class="new-todo" v-model="tianjia" />
            <button class="add" @click="tianjiafun">添加任务</button>
        </header>
        <!-- 列表区域 -->
        <section class="main">
            <ul class="todo-list">
                <li class="todo" v-for="(item,index) in shixiang" :key="item.id">
                    <div class="view">
                        <span class="index">{{index+1}}</span> <label>{{item.shiqing}}</label>
                        <button class="destroy" @click="dilite(item.id)"></button>
                    </div>
                </li>
            </ul>
        </section>
        <!-- 统计和清空 -->
        <footer class="footer">
            <!-- 统计 -->
            <span class="todo-count">合 计:<strong> {{shixiang.length}} </strong></span>
            <!-- 清空 -->
            <button class="clear-completed" @click="qingkong">
                清空任务
            </button>
        </footer>
    </section>

    <!-- 底部 -->
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
    <script>

        const app = new Vue({
            el: '#app',
            data: {
                tianjia: '',
                shixiang: [
                    { id: 0, shiqing: '吃饭' },
                    { id: 1, shiqing: '睡觉' },
                    { id: 2, shiqing: '打豆豆' },
                ],
            },
            methods: {
                // 删除模块
                dilite(id) {
                    this.shixiang = this.shixiang.filter(item => item.id !== id);
                },

                // 添加模块
                tianjiafun() {
                    // 判断是否为空，注意要使用.trim()清除两侧空格
                    if (this.tianjia.trim() === '') {
                        this.tianjia = ''
                        alert('记事不能为空！');
                        return
                    }
                    this.shixiang.unshift(
                        {
                            id: +new Date(),//用时间戳作为id，+号此处为正号，表示将new Date() 转成数字
                            shiqing: this.tianjia
                        }
                    );
                    this.tianjia = ''
                },

                // 统计模块 
                qingkong() {
                    this.shixiang = [];
                }
            }
        })

    </script>
</body>

</html>